Re: [PATCH] configure: Improve alias attribute check

[Richard Henderson]

On 3/20/21 11:52 AM, Paolo Bonzini wrote:
> > +int main(void)
> > +{
> > +    return read_y();
> > +}
>
> I think this should be "read_y() == 1 ? 0 : 1".

As a testcase returning 0 on success, yes.

> I can reproduce it with -flto -O2 but not without -flto, do you agree?

Agreed.  Replicated with a random recent gcc 11 snapshot.
This is really annoying of lto.  It's clear something needs to change though.

> Perhaps we can obtain the same optimization by wrapping reads of the page size 
> in an inline __attribute__((const)) function.  Richard, what do you think?

I'll give it a shot and see what happens.


r~